What is the role of Achillies in the Iliad?

I think that the role of Achilles is seen in a lucid form
in Book 22.  The standoff between Achilles and Hector is the moment where the pure force
of Thanatos is present in Achilles.  Fueled by his own mourning for Patrocles and
animated with a pure spirit of destruction, Achilles' savage and brutal nature is on
display at this point.  His role is to bring destruction to anyone or anything standing
in his path.  Throughout the epic, Achilles had been shown to be a brilliant warrior,
but it is at this point where his role as destroyer in its purest form is present.  The
manner in which he chases Hector down and even the vision of him approaching Hector
fulfills his role as an agent of destruction:  "The vision of Achilles in his immortal
armor must have been terrifying to send such a brave man running."  The defiling of
Hector's body and the cold manner in which Achilles disposes of his adversary help to
bring to light the savage nature of war.  Through Achilles, Homer is able to bring to
light that the bane of all glorification of Greek Society, the ability to fight in war,
is one of the most savage and barbaric practices.  This is evident in Hector in this
moment, demonstrating his role as a destructive force.